Modular turbomachine inner and outer casings with multi-stage steam extraction sites

ABSTRACT

Various embodiments include methods and apparatuses of forming turbomachine casing intermediate structures. In some embodiments apparatuses include a steam turbomachine casing intermediate structure including an inner shell having an external surface and inner shell cavity, and defining an opening for allowing fluid entry to the cavity and an outer shell having an internal surface, these surfaces defining at least one closed, axial-extending chamber, the inner shell and outer shells each having access regions adjacent the closed chamber, each of the access regions including a plurality of locations, selectable to be machined to create an exhaust slot or an exhaust opening in the inner casing or the outer casing, respectively, and wherein a structural integrity of the casing is uniform regardless of which of the axial locations are selected to be machined, where the exhaust opening is fluidly connected with the at least one closed chamber through the outer shell.

FIELD OF THE INVENTION

The subject matter disclosed herein relates generally to steam turbines.More specifically, the disclosure provided herein relates to inner andouter casings within steam turbines.

BACKGROUND OF THE INVENTION

There is often a need to extract fluid from a turboelectric machine inorder to use the fluid for an industrial process. Turbomachine casingsmay be tapped in order to extract high pressure fluid circulating withinand the high pressure fluid may be used for many different applicationswhich may include powering an adjacent machine or heating water prior toits being used as steam. The location of fluid extraction from theturbomachine casing may be chosen based on characteristics of the highpressure fluid at such a location, i.e., fluid that is extracted througha port in an upstream stage of the turbomachine will have higherpressure than fluid that is extracted from a downstream stage. Also, thesite of extraction of the fluid affects the operation of theturbomachine itself.

Conventionally, fluid extraction location is determined prior to castingof the turbomachine casing, and as discussed above, the location ofextraction is chosen based on desired fluid characteristics of the fluidand/or based on the effect that such an extraction will have on theoperation of the turbomachine.

BRIEF DESCRIPTION OF THE INVENTION

Various embodiments include intermediate structure apparatuses designedwith a plurality of possible fluid extraction locations and methods offorming same. In some embodiments, a steam turbomachine casingintermediate structure includes an inner shell having an externalsurface, wherein a material of the inner shell defines an inner shellcavity, and wherein the material of the inner shell defines an openingfor allowing fluid from a steam path of the turbomachine to enter theinner shell cavity, and an outer shell having an internal surface, theinternal surface of the outer shell and the external surface of theinner shell defining at least one closed chamber extending in an axialdirection of the steam turbomachine, the inner shell having a firstaccess region adjacent the at least one closed chamber, the first accessregion including a plurality of inner shell axial locations, wherein atleast one of the plurality of inner shell axial locations is selectableto be machined to create an exhaust slot for allowing fluid to exit theinner shell cavity and enter the at least one closed chamber, andwherein a structural integrity of the casing is uniform regardless ofwhich of the inner shell axial locations is selected to be machined, theouter shell having a second access region adjacent the at least oneclosed chamber, the second access region including a plurality of outershell axial locations, wherein at least one of the plurality of outershell axial location is selectable to be machined to create an exhaustopening fluidly connected with the at least one closed chamber throughthe outer shell and wherein the structural integrity of the casing isuniform regardless of which of the outer shell axial locations isselected to be machined.

A first aspect provides a steam turbomachine casing intermediatestructure comprising: an inner shell having an external surface, whereina material of the inner shell defines an inner shell cavity, and whereinthe material of the inner shell defines an opening for allowing fluidfrom a steam path of the turbo machine to enter the inner shell cavity;and an outer shell having an internal surface, the internal surface ofthe outer shell and the external surface of the inner shell defining atleast one closed chamber extending in an axial direction of the steamturbomachine, the inner shell having a first access region adjacent theat least one closed chamber, the first access region including aplurality of inner shell axial locations, wherein at least one of theplurality of inner shell axial locations is selectable to be machined tocreate an exhaust slot for allowing fluid to exit the inner shell cavityand enter the at least one closed chamber, and wherein a structuralintegrity of the casing is uniform regardless of which of the innershell axial locations is selected to be machined, the outer shell havinga second access region adjacent the at least one closed chamber, thesecond access region including a plurality of outer shell axiallocations, wherein at least one of the plurality of outer shell axiallocation is selectable to be machined to create an exhaust openingfluidly connected with the at least one closed chamber through the outershell and wherein the structural integrity of the casing is uniformregardless of which of the outer shell axial locations is selected to bemachined.

A second aspect provides a steam turbomachine casing intermediatestructure comprising: at least one shell casing defining at least onecavity and having a plurality of pre-formed extraction opening sitesselectable for use, wherein a structural integrity of the at least oneshell casing is uniform regardless of which of the plurality ofpre-formed extraction opening sites is selected for use.

A third aspect provides a method of fabricating a turbomachine casingstructure, the method comprising: forming a casing inner shell having anexternal surface, wherein a material of the casing inner shell definesan inner shell cavity and a fluid opening for allowing fluid from aturbomachine steam path to enter the inner shell cavity; and forming acasing outer shell having an internal surface such that the internalsurface of the outer shell and the external surface of the inner shelldefine at least one closed chamber extending in an axial direction ofthe steam turbomachine; forming, in the casing inner shell, a firstaccess region adjacent the at least one closed chamber, the first accessregion including a plurality of inner shell axial locations, wherein atleast one of the plurality of inner shell axial locations is selectableto be machined to create an exhaust slot for allowing fluid to exit theinner shell cavity and enter the at least one closed chamber, andwherein a structural integrity of the casing is uniform regardless ofwhich of the inner shell axial locations is selected to be machined; andforming, in the casing outer shell, a second access region adjacent theat least one closed chamber, the second access region including aplurality of outer shell axial locations, wherein at least one of theplurality of outer shell axial location is selectable to be machined tocreate an exhaust opening fluidly connected with the at least one closedchamber through the outer shell and wherein the structural integrity ofthe casing is uniform regardless of which of the outer shell axiallocations is selected to be machined.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this invention will be more readilyunderstood from the following detailed description of the variousaspects of the invention taken in conjunction with the accompanyingdrawings that depict various embodiments of the invention, in which:

FIG. 1 illustrates a cross sectional view of an apparatus according toembodiments of the invention.

FIG. 2 illustrates a cross-sectional view of an apparatus according toembodiments of the invention.

FIG. 3 illustrates a cross-sectional view of an apparatus according toembodiments of the invention.

FIG. 4 shows an illustrative environment according to embodiments of theinvention.

FIG. 5 shows illustrative processes that may be performed in methodsaccording to embodiments of the invention.

FIG. 6 shows illustrative processes that may be performed in methodsaccording to embodiments of the invention.

FIG. 7 shows an illustrative process that may be performed in methodsaccording to embodiments of the invention.

It is noted that the drawings of the invention are not necessarily toscale. The drawings are intended to depict only typical aspects of theinvention, and therefore should not be considered as limiting the scopeof the invention. It is understood that elements similarly numberedbetween the figures may be substantially similar as described withreference to one another. Further, in embodiments shown and describedwith reference to FIGS. 1-7, like numbering may represent like elements.Redundant explanation of these elements has been omitted for clarity.Finally, it is understood that the components of FIGS. 1-7 and theiraccompanying descriptions may be applied to any embodiment describedherein.

DETAILED DESCRIPTION OF THE INVENTION

The subject matter disclosed herein relates generally to steam turbines.More specifically, the disclosure provided herein relates to inner andouter casings within steam turbines.

As indicated herein, illustrative embodiments of turbomachine casingintermediate structures and methods of their manufacture are disclosed.Embodiments described herein include turbomachine intermediatestructures having many different possible fluid extraction locationswhich may be selected to be machined after desired characteristics ofextractable fluid are known. Intermediate structures may be produced inorder to be adapted at a later date. That is a casing intermediatestructure may be produced with a plurality of locations for potentialsteam extraction, however none of such steam extraction locations aremachined to define fluid extraction ports or openings in an intermediatestructure. Intermediate structures are useful because a single, modulardesign may be modified in many different ways, after designcharacteristics are known. That is, such characteristics may not beknown at the time of creation of the casing, therefore a the creating ofa casing intermediate structure having a plurality of possible fluidextraction locations allows a single intermediate casing to be used in aplethora of potential applications. As differentiated from conventionalturbomachine casings which have pre-formed or pre-machined fluidextraction sites, embodiments described herein include intermediatestructures and methods of forming same which allow for very manypossible fluid extraction sites and combinations of sites.

Turning to FIG. 1, a cross sectional view of an apparatus according toembodiments of the invention is shown. FIG. 1 illustrates casingintermediate structure 100 having inner shell 110. Inner shell 110 isdesigned to encase a plurality of stages 130 of steam turbomachine 10and to enclose part of a steam path from steam inlet 140 to a steamextraction location such as slot 150 or 250, the latter described belowwith respect to FIG. 2. Inner shell 110 has an external surface 115. Thematerial of inner shell 110 defines an inner shell cavity 155 and anopening such as exhaust slot 150. Exhaust slot 150 is machined into oneof a plurality of inner shell axial locations 175. Exhaust slot 150, inaxial location 175 allows fluid to exit steam path 130 and enter innershell cavity 155.

Inner shell cavity 155 may be cast at the time of creation of innershell 110, in some embodiments. It is understood that, according toembodiments, the inner shell cavity 155 is entirely contained within theinner shell 110. Intermediate structure 100 also includes outer shell120. Outer shell 120 is illustrated surrounding inner shell 110 andhaving an internal surface 125. Internal surface 125 of outer shell 120and external surface 115 of inner shell 110 define at least one closedchamber 160 extending in an axial direction A of the steam turbomachine10. Inner shell 110 has a first access region 170 adjacent the at leastone closed chamber 160. First access region 170 includes a plurality ofinner shell axial locations 175, (inner shell axial locations 175 shownin FIG. 3). According to embodiments, at least one axial location 175 ofthe plurality of inner shell axial locations 175 is selectable to bemachined to create exhaust slot 150. Inner shell axial locations 175 aresections of inner shell 120 which may be machined for extraction offluid from an adjacent closed chamber 160. According to embodiments ofthe invention, inner shell axial locations 175 may, as a whole, definean elongated shape, extending in an axial direction A of turbomachine10. Inner shell axial locations 175 may be located in inner shell 110,contiguous to one another; that is, there may be no distinct separationbetween two adjacent inner shell axial locations 175. Inner shell axiallocations 175 define potentially machinable areas of inner shell 120 forcreation of fluid extraction. The creation of exhaust slot 150 bymachining a selected inner shell axial location 175 is performed whilemaintaining a structural integrity of casing intermediate structure 100,and the structural integrity remains uniform regardless of which of theinner shell axial locations 175 is selected to be machined. It should beunderstood that the terms “slot” and “opening” are used to differentiatebetween the ports through the inner and outer casings, 110 and 120,respectively; no other differences between “slot” and “opening” need beinferred.

The creation of inner shell 110 with the plurality of machinable axiallocations 175 allows for a designer to select fluid extraction locationswhen desired characteristics of extracted fluid are known. As describedabove, an inner shell axial location 175 adjacent an upstream stage of aturbomachine 10 may be machined in order to extract high pressure fluid,if a designer determines that high pressure fluid is desired for aparticular industrial purpose. Likewise, fluid may be extracted frominner shell axial locations adjacent other stages of turbomachine 10according to the needs of the designer and the pressure or othercharacteristics of the fluid within such stages, such characteristicsmay include, but are not limited to moisture content or temperature.

According to embodiments, outer shell 120 includes a second accessregion 180 adjacent at least one closed chamber 160, and second accessregion 180 includes a plurality of outer shell axial locations 185(shown in FIG. 3). Outer shell axial locations 185 are locations whichmay be machined to create a fluid extraction port, e.g. an opening 190,from closed chamber 160. According to embodiments, at least one of theplurality of outer shell axial locations 185 is selectable to bemachined to create an exhaust opening 190 fluidly connected with the atleast one closed chamber 160 through outer shell 120. The creation ofthe exhaust opening 190 by machining is performed while maintaining thestructural integrity of the casing 100 and the structural integrityremains uniform regardless of which of the outer shell axial locations185 is selected to be machined.

Inner shell 110 and outer shell 120 may be formed by casting using atleast one of steel, nickel, chromium or alloys thereof, e.g., ferriticsteel, ferritic-martensitic steel, austenitic stainless steel, 2.25 Cr-1Mo steel, 1-2 CrMo steel, etc. Other materials may be used as known bythose skilled in the art. The casting of the shells maybe performedusing molds. The inner and outer shells 110, 120, respectively, may becreated at the same time, using the same mold, or they may be createdseparately, using different sets of molds. The at least one closedchamber 160 may be created as follows. First, internal surface 125 ofouter shell 120 and external surface 115 of inner shell 110 may bedefined by at least one mold. Then molten metal may be poured into amold, or molds, as appropriate. A core may be inserted into the mold(s)in order to create the surfaces defining at least one chamber 160. Sucha core may comprise sand which is inserted into the mold space prior tothe pouring of the molten metal. When the metal solidifies, the core isremoved, creating the at least one chamber 160. At this stage, it shouldbe understood that the chamber may need to be cleaned of any debris,e.g., remaining sand. The casting process described enablesaccessibility for cleaning of the chamber 160 after solidification ofmetal casting and core removal.

Turning to FIG. 2, a cross-sectional view of an apparatus according toembodiments is shown. FIG. 2 illustrates an embodiment having innershell 110 including first and second axial sections, 117 and 119,respectively. Furthermore, FIG. 2 illustrates options for embodimentsaccording to aspects. In some embodiments, steam extraction exhaust slot250 may be in a position different from steam extraction exhaust slot150, as illustrated in FIG. 2.

According to embodiments, inner shell 110 may include separate first andsecond axial sections 117 and 119, the axial sections 117 and 119 areshaped complementary to one another, with a 360 degree fit 135, actingas a dividing wall or support between axial sections 117, 119. Inembodiments that include first and second axial sections 117 and 119 ofinner shell 110, at least one first stage 132 may be supported on firstaxial section 117, and at least one second stage 134 may be supported onsecond axial section 119 as illustrated in FIG. 2. It should beunderstood that the first and second stages, 132 and 134 are stationarystages of turbomachine 10. Such stationary stages may include, but arenot limited to nozzle stages.

Exhaust slots 150 and 250, shown in FIGS. 1 and 2, respectively, allowextraction of a high pressure fluid from inner shell 110 at a steamextraction location, such as slot 150 or 250, proximate a selected stage130, (selected stage not specifically shown) of steam turbomachine 10,the steam extraction location, such as slot 150 or 250, being related toa fluid characteristic of the fluid within steam turbomachine 10 inoperation. Such fluid characteristics are described above with respectto FIG. 1 and will not be repeated for the sake of brevity. According toembodiments, fluid, such as steam may be released via slots 150 adjacentvarious stages 130. In embodiments where fluid, such as steam isextracted from a location 150/250 upstream of second axial section 117,the outer shell may be machined to allow for extraction of fluidupstream of the 360 degree fit 135 and second axial section 119 may notbe machined (opened) to allow for fluid extraction therefrom. Inembodiments where machined extraction locations are desired adjacentsecond axial section 119, the outer casing 120 may be machined to allowfor fluid extraction downstream of 360 degree fit 135 and in suchembodiments, second axial section 119 lies adjacent a closed chamber 160designed specific to that particular stage.

According to embodiments, inner shell cavity 155 may be sealed by aclosure, such as plate 176. Such closure may be accomplished usingnow-known or later-developed fabrication techniques, including, e.g.,welding, or casting of plate 176. Exhaust slot 150 in axial location 175may be machined by access through steam path 130 directly, inembodiments using multiple inner shells 110. According to otherembodiments, opening 175 may be created by machining plate 176 to allowfluid flow from closed chamber 160. Such procedures may for example beperformed in embodiments having single or multiple inner shell casingsections. According to embodiments having a single inner casing 110 orembodiments having first and second axial sections 117, 119,respectively, of inner casing 110, the fluid characteristic may be acharacteristic of steam. Such a characteristic may include, but are notlimited to: pressure, moisture content (wetness), temperature, flowrate. In either case, steam may be released via steam extractionlocation, such as slot 150 or 250 proximate a selected stage 130 of theturbomachine 10. As discussed above, this steam (or fluid) may be usedfor an industrial process or it may be sent to a boiler feed waterheater to alter (e.g., to increase) cycle efficiency.

According to embodiments, one of a plurality of axial locations 175 maybe selected to be machined in order to allow for extraction of fluid,from exhaust opening 190 proximate a relatively upstream stage of thesteam turbine, in order to allow extraction of a relatively highpressure fluid from the at least one closed chamber 160 proximate aselected stage of the turbomachine 10. Alternatively exhaust slot 150may be selected in order to extract fluid from an exhaust opening 190proximate a relatively downstream stage of the previously mentionedupstream stage in order to extract a lower pressure fluid. The locationof fluid extraction may determine the fluid characteristics of theextracted fluid.

FIG. 3 illustrates a cross-sectional view of an apparatus according toembodiments. FIG. 3 illustrates an embodiment where first and secondaccess regions 170 and 180, respectively, each have a uniform thicknessT1, T2 respectively, different from a thickness of the inner shell 110adjacent first access region 170 and different from a thickness of theouter shell 120 adjacent second access region 180. According to someembodiments, first access region 170 has a thickness T1 that is lessthan half a thickness of a remainder of inner shell 110. And likewise,according to embodiments, second access region 180 has a thickness T2that is less than half a thickness of a remainder of the outer shell120.

FIG. 3 further illustrates an embodiment where internal surface 125 ofouter shell 120 and external surface 115 of inner shell 110 define atleast two closed chambers 160 extending in an axial direction A of thesteam turbomachine 10. While only two chambers 160 are illustrated inFIG. 3, any number of closed chambers 160 may be created. It should benoted that the intermediate structures described herein, are designed toallow for fluid extraction at any of a number of locations 175, butactual extraction at a plurality of locations within the sameturbomachine is not necessary according to all embodiments of theinvention.

According to embodiments of the invention, a steam turbomachineintermediate structure may have at least one shell casing having aplurality of pre-formed extraction opening sites selectable for use,wherein a structural integrity of the at least one shell casing isuniform, regardless of which of the plurality of pre-formed extractionopening sites is selected for use. The at least one shell casingaccording to this embodiment is analogous to the inner and outer shellcasings, 110 and 120, described herein above with respect to FIGS. 1-3.Also, the pre-formed extraction opening sites according to suchembodiments are analogous to inner shell axial locations 175 and outershell axial locations 185 described herein above with respect to FIGS. 1and 3, respectively. According to such an embodiment, an extractionopening may be selected to be used based on the location of the opening.That is, an opening may be selected because it is adjacent a relativelyupstream stage in the steam turbo machine and because a designer desiresto access high pressure steam for use in an industrial process.Likewise, an extraction opening may be selected due to its proximity toa relatively downstream stage because a designer chooses to access steamfrom the turbomachine having a different fluid characteristic than steamfrom an upstream stage. For non-limiting example a designer may needrelatively high moisture content (wet) steam or relatively lowtemperature steam for an industrial purpose and therefore the designermay use an extraction opening appropriate for this desired industrialpurpose.

According to embodiments of the invention the at least one casing may bean inner casing having first and second axial sections 117 and 119, asdescribed above with respect to FIG. 2. And according to embodiments ofthe invention, the pre-formed extraction opening site may selected foruse based on one or more fluid characteristics of a fluid within thesteam turbomachine during operation, adjacent the selected opening site.Such fluid characteristics are described herein and will not be repeatedhere, for the sake of brevity.

FIG. 4 illustrates an environment according to embodiments of theinvention. System 300 includes a dynamoelectric machine 305 and a steamturbomachine 10 coupled with the dynamoelectric machine 305. Steamturbomachine 10 as illustrated, includes steam turbomachine casingintermediate structure 100 as described above with respect to FIGS. 1-3,and such description will not be repeated for the sake of brevity. Someembodiments of the invention include a gas turbine 320 fluidly connectedwith generator 340, as illustrated in FIG. 4. Embodiments may furtherinclude heat recovery steam generator (HRSG) 330 fluidly coupled withthe gas turbomachine 320 and the steam turbomachine 10, as illustratedin FIG. 4. Embodiments of the invention may also include generator 340operationally connected with gas turbine 320 or alternatively with steamturbomachine 10 (such connection is not shown in FIG. 4).

FIG. 5 illustrates processes in a method of fabricating a turbomachinecasing structure according to embodiments of the invention. Process P100is illustrated in FIG. 5 and includes, forming a casing inner shellhaving an external surface, wherein a material of the casing inner shelldefines an inner shell cavity and a fluid opening for allowing fluidfrom a turbomachine steam path to enter the inner shell cavity. ProcessP110 may be performed concurrently with, or after process P100 andincludes forming a casing outer shell having an internal surface suchthat the internal surface of the outer shell and the external surface ofthe inner shell define at least one closed chamber extending in an axialdirection of the steam turbomachine. It should be understood that thetiming of performance of processes P100 and P110 may not be affect themethod as a whole. Processes P100 and P110 may include casting asdescribe above which will not be repeated for the sake of brevity.Optional Process P115, shown in FIG. 6, includes forming a casing innershell and the forming of the casing outer shell such that the outersurface of the casing inner shell and the inner surface of the casingouter shell define at least two closed chambers extending in an axialdirection of the steam turbomachine. According to embodiments, optionalprocess P115 may be performed in lieu of processes P100 and P110, orprocess P115 may be performed as an embellishment to processes P100 andP110.

Referring back to FIG. 5, process P120 includes forming, in the casinginner shell, a first access region adjacent the at least one closedchamber, the first access region including a plurality of inner shellaxial locations. The first access region may be formed of casingmaterial of a different thickness than adjacent casing material. As anon-limiting example, the first access region may be cast of steelhaving a thickness half of the thickness of the steel that makes up theinner casing adjacent to the first access region. According toembodiments, each of the plurality axial locations within the innershell is selectable to be machined to create an exhaust slot forallowing fluid to exit the inner shell cavity and enter the at least oneclosed chamber. As discussed above, an exhaust slot may be located toallow high pressure fluid, such as steam, to flow from the inner shelland into one or more of the closed chambers. Any machining performed tocreate an exhaust slot maintains the structural integrity of the casinguniformly, regardless of which of the inner shell axial locations may beselected to be machined. According to aspects, the forming of the firstaccess region may include forming the first access region to have auniform thickness, different from a thickness of the inner shelladjacent the first access region. Also according to aspects the formingof the first access region may include forming the first access regionto have a thickness less than half a thickness of the remainder of theinner shell.

According to embodiments, the inner shell casing may be formed usingoptional process P124, which is illustrated in FIG. 7. Optional processP124 includes forming the casing inner shell by forming a first axialsection and forming a second axial section, the second axial sectionbeing separate from and complementary to the first axial section.

Referring back to FIG. 5, process P125 includes forming, in the casingouter shell, a second access region adjacent the at least one closedchamber, the second access region including a plurality of outer shellaxial locations, wherein at least one of the plurality of outer shellaxial location is selectable to be machined to create an exhaust openingfluidly connected with the at least one closed chamber through the outershell and wherein the structural integrity of the casing is uniformregardless of which of the outer shell axial locations is selected to bemachined. According to aspects, the forming of the second access regionmay include forming the second access region to have a uniformthickness, different from a thickness of the outer shell adjacent thesecond access region. Also according to embodiments, the forming of thesecond access region may include forming the second access region tohave a thickness less than half a thickness of a remainder of the outershell.

FIG. 5 shows optional processes P130 and P140. Optional process P130includes machining a first slot through the first access region, whereina location of the first slot is based upon a performance characteristicof the turbomachine. Optional process P140 includes machining a firstopening in the second access region, the first opening extending throughthe outer shell. Such locations and associated performancecharacteristics where discussed above with respect FIG. 1 and will notbe repeated for the sake of brevity.

Optional processes P150 and P160 are illustrated in FIG. 6; optionalprocessed P150 and P160 may be performed after optional process P115.Optional process P150 includes machining a second slot through the firstaccess region into a second of the at least two closed chambers whilemaintaining the structural integrity of the casing, a location of thesecond slot being based upon a performance characteristics of theturbomachine Optional process P150 may be performed, for example incases where a designer may desire two outputs from a steam turbine andwhere the designer desires fluid having different characteristics toperform different functions. For example a designer may desire fluid ofrelatively high pressure for some industrial process and therefore thedesigner may locate a first slot adjacent an upstream stage of a steamturbomachine. The designer may also desire lower pressure fluid tooperate a different industrial application, and the designer may locatea second slot adjacent a stage downstream of the first slot to attainsuch relatively lower pressure fluid. While two slots located adjacentdifferent stages are discussed, embodiments of the invention may includeany number of slots, located adjacent the same or different stages of asteam turbomachine without deviating from the spirit of the invention.

Optional process P160 includes machining a second opening in the secondaccess region adjacent the second of the at least two closed chamberswhile maintaining the structural integrity of the casing, the secondopening extending through the outer shell. According to embodiments, asecond opening may allow a designer to access fluid from a secondlocation to be used for a second industrial purpose. It should be notedthat the slots and openings described herein are not necessarilyintended to remain open or to constantly allow release of fluid. Suchopenings and slots may be capped, and/or valves may be used to allow forrelease of fluid only when desired. Optional processes P150 and P160 maybe performed subsequent to process P115, in which a plurality of closedchambers is defined.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

As used herein, the terms “axial” and/or “axially” refer to the relativeposition/direction of objects along axis A, which is substantiallyparallel with the long axis of a conduit at a pipe crossing. As furtherused herein, the terms “radial” and/or “radially” refer to the relativeposition/direction of objects along radius (r), which is substantiallyperpendicular with axis A and intersects axis A at only one location.Additionally, the terms “circumferential” and/or “circumferentially”refer to the relative position/direction of objects along acircumference which surrounds axis A but does not intersect the axis Aat any location.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A steam turbomachine casing intermediatestructure comprising: an inner shell having an external surface, whereina material of the inner shell defines an inner shell cavity, and whereinthe material of the inner shell defines an opening for allowing fluidfrom a steam path of the turbomachine to enter the inner shell cavity;and an outer shell having an internal surface, the internal surface ofthe outer shell and the external surface of the inner shell defining atleast one closed chamber extending in an axial direction of the steamturbomachine, the inner shell having a first access region adjacent theat least one closed chamber, the first access region including aplurality of inner shell axial locations, wherein at least one of theplurality of inner shell axial locations is selectable to be machined tocreate an exhaust slot for allowing fluid to exit the inner shell cavityand enter the at least one closed chamber, and wherein a structuralintegrity of the casing is uniform regardless of which of the innershell axial locations is selected to be machined, the outer shell havinga second access region adjacent the at least one closed chamber, thesecond access region including a plurality of outer shell axiallocations, wherein at least one of the plurality of outer shell axiallocation is selectable to be machined to create an exhaust openingfluidly connected with the at least one closed chamber through the outershell and wherein the structural integrity of the casing is uniformregardless of which of the outer shell axial locations is selected to bemachined.
 2. The steam turbomachine casing of claim 1, wherein the innershell includes a first axial section and a second axial section separatefrom and complementary to the first axial section.
 3. The steamturbomachine casing of claim 1, wherein the exhaust slot allowsextraction of a high pressure fluid from the inner shell at a locationproximate a selected stage of the turbomachine, the location beingrelated to a fluid characteristic.
 4. The steam turbomachine casing ofclaim 1, wherein the exhaust opening allows extraction of a highpressure fluid from the at least one closed chamber proximate a selectedstage of the turbomachine.
 5. The steam turbomachine casing of claim 1,wherein the first and second access regions each have a uniformthickness, different from a thickness of the inner shell adjacent thefirst access region and different from a thickness of the outer shelladjacent the second access region.
 6. The steam turbomachine casing ofclaim 5, wherein the first access region has a thickness that is lessthan half a thickness of a remainder of the inner shell.
 7. The steamturbomachine casing of claim 5, wherein the second access region has athickness that is less than half a thickness of a remainder of the outershell.
 8. The steam turbomachine of claim 1, wherein the internalsurface of the outer shell and the external surface of the inner shelldefine at least two closed chambers extending in an axial direction ofthe steam turbomachine.
 9. A steam turbomachine casing intermediatestructure comprising: at least one shell casing defining at least onecavity and having a plurality of pre-formed extraction opening sitesselectable for use, wherein a structural integrity of the at least oneshell casing is uniform regardless of which of the plurality ofpre-formed extraction opening sites is selected for use.
 10. The steamturbomachine casing intermediate structure of claim 9, wherein the atleast one shell casing includes an inner shell casing and an outer shellcasing, wherein the at least one cavity is defined by a material of theinner shell.
 11. The steam turbomachine casing intermediate structure ofclaim 10, wherein the inner shell casing includes a first axial sectionand a second axial section.
 12. The steam turbomachine casingintermediate structure of claim 9, wherein the pre-formed extractionopening site is selected for use based on a fluid characteristic of afluid within the steam turbomachine during operation adjacent theselected opening site.
 13. A method of fabricating a steam turbomachinecasing structure for a steam turbomachine, the method comprising:forming a casing inner shell having an external surface, wherein amaterial of the casing inner shell defines an inner shell cavity and afluid opening for allowing fluid from a turbomachine steam path to enterthe inner shell cavity; and forming a casing outer shell having aninternal surface such that the internal surface of the outer shell andthe external surface of the inner shell define at least one closedchamber extending in an axial direction of the steam turbomachine;forming, in the casing inner shell, a first access region adjacent theat least one closed chamber, the first access region including aplurality of inner shell axial locations, wherein at least one of theplurality of inner shell axial locations is selectable to be machined tocreate an exhaust slot for allowing fluid to exit the inner shell cavityand enter the at least one closed chamber, and wherein a structuralintegrity of the casing is uniform regardless of which of the innershell axial locations is selected to be machined; and forming, in thecasing outer shell, a second access region adjacent the at least oneclosed chamber, the second access region including a plurality of outershell axial locations, wherein at least one of the plurality of outershell axial location is selectable to be machined to create an exhaustopening fluidly connected with the at least one closed chamber throughthe outer shell and wherein the structural integrity of the casing isuniform regardless of which of the outer shell axial locations isselected to be machined.
 14. The method of claim 13, wherein the formingof the casing inner shell includes: forming a first axial section; andforming a second axial section, the second axial section being separatefrom and complementary to the first axial section.
 15. The method ofclaim 13, further comprising: machining a first slot through the firstaccess region, wherein a location of the first slot is based upon aperformance characteristics of the turbomachine; and machining a firstopening in the second access region, the first opening extending throughthe outer shell.
 16. The method of claim 13, wherein the forming of thecasing inner shell and the forming of the casing outer shell areperformed such that the outer surface of the casing inner shell and theinner surface of the casing outer shell define at least two closedchambers extending in an axial direction of the steam turbomachine. 17.The method of claim 16, further comprising: machining a second slotthrough the first access region into a second of the at least two closedchambers while maintaining the structural integrity of the casing, alocation of the second slot being based upon a performancecharacteristics of the turbomachine; and machining a second opening inthe second access region adjacent the second of the at least two closedchambers while maintaining the structural integrity of the casing, thesecond opening extending through the outer shell.
 18. The method ofclaim 13, wherein the forming of the first access region includesforming the first access region to have a uniform thickness, differentfrom a thickness of the inner shell adjacent the first access region.19. The method of claim 13, wherein the forming of the second accessregion includes forming the second access region to have a uniformthickness, different from a thickness of the outer shell adjacent thesecond access region.
 20. The method of claim 13, wherein the forming ofthe first access region includes forming the first access region to havea thickness less than half a thickness of the remainder of the innershell; and wherein the forming of the second access region includesforming the second access region to have a thickness less than half athickness of a remainder of the outer shell.